Background: Intrathecal opioid is an effective and well accepted technique for postoperative pain control. However, the high incidence of morphine induced pruritus when administered intrathecally make parturient patients uncomfortable. At Ramathibodi Hospital, the protocol for prophylaxis andtreatment of morphine induced pruritus is not yet well established.

Objective: To assess the efficacy of ondansetron and ketorolac in preventing pruritus from intrathecal morphine in parturient patients.

Methods: This double-blinded RCT consisted of sixty-four parturient patients, ASA 1-3 who were planned for cesarean section under spinal block with 0.5% heavy Marcaine and 0.2 mg. of intrathecal morphine. They were random by assigned into 2 groups: intervention group (I), receiving ondansetron 4 mg and ketorolac 30 mg after routine antibiotic administration and controlled group(C) which would receive placebo with NSS in equal amount. All the subjects were asked questions about: pruritus, nausea/vomiting and pain score. These data were recorded 6 times: at the end of operation, before leaving PACU, an arrival at ward and at 6, 12, 24 hour after spinal block. At the end of study, the patients were asked to rate satisfaction score.

Results: Comparing to the control group, the pruritus intensity score were statistically significant lower in I-group at 6, 12 and 24 hour after spinal morphine. Request for metoclopramide was, significantly lower in I-group at the end of operation. The incidence of

nausea/vomiting and severity of pain, as well as satisfaction scores were not different between the two groups at any point of measurement.

Conclusions: Ondansetron and ketorolac showed favorable effect in pruritus prophylaxis and antiemetic in patients undergoing cesarean section receiving intrathecal morphine.